Generally, direct conversion receivers receive radio signals and down convert received radio signals to baseband where information from the received radio signals may be obtained. Such direct conversion receivers can include high performance mixers. An exemplary high performance mixer is disclosed in U.S. Pat. No. 6,230,000 to D. Tayloe issued May 8, 2001 and entitled “PRODUCT DETECTOR AND METHOD THEREFOR,” the contents of which are incorporated by reference herein. High performance mixers can be realized in electrical circuitry such as Complementary metal-oxide-semiconductor (CMOS) and disadvantageously can have high capacitance which draws a high current (and thus high power) on each switch cycle of the mixer. Conventionally, such direct conversion receivers and high performance mixers are used in mobile and portable devices. Power drain is critical to such mobile and portable devices which utilize batteries for power. Accordingly, to support extended battery life, there is a need for dynamic sub-sampling mixer systems and methods which adjust a sub-sampling rate based on power drain and performance. That is, there is a need for dynamic sub-sampling mixer systems and methods which vary the sub-sampling ratio based on a required noise figure, which can also be defined as low signal level performance, of the associated receiver.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.